Eaton Char-Lynn Motor Describes Motor Fsi Technology
FSI means fuel stratified injection. The fuel stratified injection technology is one of the motor lean-burn technologies. What is lean burning? As the name implies, the gasoline content in the motor mixture is low, and the ratio of gasoline to air can reach 1:25 or more.
The Volkswagen FSI motor utilizes a high pressure pump to pass gasoline through a split rail (common rail) to the electromagnetically controlled high pressure injection valve. It is characterized in that a variable eddy current has been generated in the intake passage, so that the intake air flow forms an optimal vortex form into the combustion chamber, and is pushed by the layered filling, so that the mixed gas is concentrated around the spark plug located in the center of the combustion chamber. If the mixing ratio of the lean-burning technology reaches 25:1 or more, it is conventionally impossible to ignite, so a stratified combustion method from rich to lean must be employed. Through the movement of the air in the cylinder, a dense mixture which is easy to ignite is formed around the spark plug, the mixing ratio is about 12:1, and the outer layer is gradually thin. After the rich mixture is ignited, the combustion quickly spreads to the outer layer.
The FSI features: it can reduce pumping losses and ensure low fuel consumption at low loads, but requires special catalytic converters to effectively purify the exhaust gases. The following are elaborated separately:
Eaton Char-lynn Motor Description: The FSI motor can basically select two operating modes according to the motor load conditions. It is stratified lean combustion at low load and homogeneous theoretical air-fuel ratio (14.6-14.7) at high load. In both modes of operation, the injection time of the fuel is different, and the vacuum-operated on-off valve is opened/closed. In homogeneous theoretical air-fuel ratio combustion performed at high loads, fuel is injected during the intake stroke. The homogeneous mixture of the theoretical air-fuel ratio is easy to burn without the aid of eddy currents, and therefore, the switching valve is opened due to a decrease in intake resistance. Except for the full load, the exhaust gas recirculation is performed to limit the pumping loss, and the compression ratio is increased to 12.1 due to the direct injection, so that the fuel consumption can be reduced even in the homogeneous theoretical air-fuel combustion. Further, in the FSI motor, between the low load and the high load, a homogeneous lean burn is set as the third operation mode, in which the fuel is injected in the intake stroke, and due to the generation of the accelerated lean mixing The longitudinal vortex of the gas combustion, the on-off valve is closed. At this time, exhaust gas recirculation (EGR) that hinders combustion is temporarily not performed. Unlike homogeneous theoretical air-fuel ratio combustion, the amount of intake air exceeds the amount of fuel injected.
As described above, according to the FSI motor operating state, the air-fuel ratio continuously changes during the stratified lean combustion to the homogeneous theoretical air-fuel ratio combustion process. Therefore, the three-way catalytic converter is not capable of purifying NOx in the exhaust gas. This is because the three-way catalytic converter utilizes HC or CO in the exhaust gas for the NOx reduction reaction. In lean combustion, a lot of oxygen remains in the exhaust gas, and the NOx reduction reaction cannot be performed. In order for the NOx occlusion catalyst to function efficiently, its temperature must be maintained in the range of 250-500 °C. When this temperature range is exceeded, the motor will automatically switch to homogeneous theoretical air-fuel ratio combustion and exhaust gas treatment through a three-way catalytic converter. However, this is in turn associated with a drop in fuel economy, for which reason the exhaust gas cooling device must be added. With such a cooling device, the exhaust gas is cooled by NOx storage type catalytic conversion, and the life of the catalytic converter is also prolonged due to the wide range of lean combustion. However, the NOx storage type catalytic converter is poisoned by sulfur attack, so the sulfur content in the gasoline must be minimized as much as possible. However, as mentioned earlier, gasoline with low sulfur content is not available everywhere. Volkswagen’s approach is to increase the catalyst reaction temperature above 650° to eliminate the sulfur attached to the catalyst by combustion.
At such a high speed, the catalyst temperature can be maintained at a high speed. However, when the temperature of the catalyst is lowered while traveling in a city, the sulfur adhering to the catalyst cannot be burned off. To this end, the extent to which sulfur adheres to the catalyst is monitored by the NOx sensor, and the temperature of the exhaust gas is increased in accordance with the monitoring condition. As a measure, ignition timing retardation is generally employed, although this may cause deterioration in fuel economy, but it is a last resort to purify NOx.